This invention relates to an air vent assembly for use in conjunction with heat-recoverable closures when used to seal, repair and/or protect pressurized cables. The air vent assembly, in conjunction with a heat-recoverable closure, can also be used to provide access to pressurized air in the cable.
Heat-recoverable closures, such as, tubular sleeves, wraparound sleeves and tape are used to form a protective covering around elongate substrates such as cables, including pressurized and non-pressurized telephone cables. The heat-recoverable sleeve or tape is generally coated with a layer of mastic or an adhesive, preferably a hot melt adhesive. Alternatively the adhesive may be applied in the form of a tape, sheet or sleeve positioned around the cable, or other substrate before placing the heat-recoverable closure around the substrate. Heating of the closure causes the closure to recover and the adhesive to melt and flow. Upon cooling, a pressure and watertight seal results. It has been found that when such a protective system is used with pressurized cables, pressurized air escaping from the cable forces its way through the molten adhesive, resulting in leakage pathways and inadequate sealing between the heat-recovered sleeve or tape and the cable. To avoid this result, it is often necessary or desirable to depressurize the cable prior to and during the heat-recovery step. To avoid depressurizing the cable, a pressure access flange is sometimes used. However, this requires making a hole or slit in the heat-recoverable closure to accomodate the outlet of the pressure access flange. This hole in the closure can cause splitting along the length of the closure during the heat-recovery step.